A multi-mode single-standby phone can support multiple network communications such as LTE, TD, WCDMA, GSM. However, the multi-mode single-standby phone can operate at only one network standard at the same time and CSFB (Circuit Switched Fallback) is supported. In a case that a network of the multi-mode single-standby phone is selected according to default priority, the 4G network is preferential, and the network of the multi-mode single-standby phone will reside in the 4G network.
There is a problem in the conventional technology that, a busy line is prompted for an incoming call in a case that the network of the multi-mode single-standby phone resides in the 4G network in an area where the CSFB is not supported, which results in missing the incoming call.
Therefore, a new technical solution is required, to prevent a user from missing the incoming call in the area where the CSFB is not supported.